In the older German Patent Application No. P 35 36 710.5, an installation for harnessing thermal energy operating as a heat converter has been proposed, having a substantially cylindrical housing that includes three chambers, which are at different temperatures. Two positive displacement regenerators are disposed in the housing, which are moved by a gear either in alternation or with phase displacement, in such a way that with cyclic repetition,
(a) gaseous working fluid, such as helium, is transferred by the first positive displacement means from the middle work chamber, which is at a temperature in a predetermined, medium temperature range, into a "hot" working chamber, which is at a temperature in a higher temperature range than the first, and thermal energy is supplied to the transferred gas; PA1 (b) working fluid is transferred by the second positive displacement regenerator from the middle work chamber into a "cold" work chamber, which is at a temperature in a relatively low temperature range, which is lower than the first temperature, and thermal energy is removed from the transferred working fluid; PA1 (c) working fluid is transferred by the first positive displacement regenerator from the hot work chamber into the middle work chamber, and thermal energy is removed from the transferred working fluid; PA1 (d) working fluid is transferred by the second positive displacement means from the cold work chamber into the middle work chamber, and thermal energy is supplied to the transferred working chamber; and PA1 (e) working fluid is transferred by the first and second positive displacement regenerators from the hot work chamber into the cold work chamber, and thermal energy is removed from the working fluid.
A disadvantage of the proposed heat converter is that the work chambers located at different temperatures are located in the same housing and therefore cannot be completely thermally insulated from one another, which results in heat losses and hence a reduction in efficiency.
From German Patent Document DE-A-No. 32 37 841, a thermally operated heat pump is known, which comprises two identical units each having a high-temperature and low-temperature working cylinder with corresponding positive displacement pistons, the periodic reciprocation of which is out of phase by 90.degree. with one another, while the phases of the corresponding positive displacement pistons in the two units are displaced by 180.degree. from one another. Both units each include a constant volume that is hermetically sealed off from the outside and is filled with compressed gas, heat at a relatively high temperature is supplied to both high-temperature cylinders, while a much greater heat at a lower temperature is supplied to the low-temperature cylinders, and the waste heat of all four cylinders is removed as useful heat. For the high-temperature cylinder, a countercurrent heat exchanger is provided, the two pipe systems of which connect the upper work chambers with the lower work chambers. The work chambers, separated by the positive displacement means, of the two low-temperature cylinders communicate with one another by means of the separate pipe systems of a second heat exchanger. Once again, however, a temperature difference must be maintained along the cylinders, so that once again problems arise with respect to the thermal insulation.